my grandmothers pt cruiser did the same thing when her car was a tooth off with her timing belt i wouldnt say it couldnt be it but im like yak i would start small if you have changed your tps it might could be your ICS it wouldnt idle correctly and would cause the drop in RPMs due to the the malfunction of it

 

how do i do that???? i unhooked the battery and let it sit over night after i put the O2 sensor in...

 

i havent changed the TPS or the ICS.... what is the ICS???

 

idle control sensor

 

so its different from the TPS right?

 

i probably need to change the timing chain and gears anyhow... lol almost 290k miles! still a champ just rough idle. lol

 

yes the idle control sensor is on the throttle body in the front or the back cant remember off hand but it controls the air flow into the engine at idle sort of acts like a choke when you start the truck

 

i know the one thats in the back of my throttle is the IAC... and the one on drivers side is the TPS... something in front where vac attaches... but idk?

 

ye the IAC my family calls it the idle control sensor :P

 

ok. i see what u mean now....
i should replace both... f it! lol